Fuel pipelines of current aircraft are usually made of metal (e.g. aluminum, stainless steel or titanium), as are the wings in which they are housed. Nevertheless, for several years now wings and fuel pipelines have started to be designed in composite materials, so as to lighten as much as possible these pipelines and the wing units incorporating them (e.g. the wing unit, central box section or engine strut) or to reduce the electrical conductivity of these pipelines to prevent risks of lightning strike, notably in the case where these pipes are fixed to the structures that are themselves composite and are therefore less conductive than metal.
Reference may be made for example to document WO-A1-2006/136597 for an example of a composite ducting comprising two coaxial inner and outer conduits separated by struts and that are at least partly made of a composite thermosetting material, such as an epoxy resin reinforced by carbon fibers. Mention may also be made of document EP-A1-1 878 562 that teaches the production of ducting for air-conditioning lines designed for aircraft, incorporating pipes with thermoplastic or thermosetting plies, for example based on a phenolic resin for the thermosetting matrix.
Currently, most three-dimensional pipes are made of metal, being obtained by bending or welding. They are thus relatively heavy, on account of the high density of the metallic material used. Composites thus represent a valuable solution for lightening these pipes, notably for the pipes of fuel lines or hydraulic lines or aeronautical extinguisher lines, where weight is an important factor in performance, economy and the reduction of consumption and emissions.
However, when pipes are made of a composite material with a three-dimensional shape, their production requires:                a rigid mold associated with an inflatable bag of which the role is to apply the wall of the pipe with pressure into the mold, or        a rigid core (of the extractable, fusible or soluble type for example) on which either dried reinforcing fibers are draped that are infused under vacuum and then cured in an oven, or prepregs, (i.e. material in sheets impregnated with a thermosetting resin of which polymerization is incomplete) that are consolidated and then cured in an autoclave.        
A major disadvantage of these known pipes and the methods for producing them lies in their relatively high cost, since they require costly equipment (molds and bags in particular) as well as costly cores (case of extractible cores, for example), cores that have to be replaced regularly after producing several tens of parts (e.g. inflatable bags, flexible mandrels) or even lost cores for each part produced (case of soluble or fusible cores).